Generally, an insert tip is an element of a cutter used to work steel or cast iron and is made of cemented carbide. The insert tip is fixed to a cutter body of steel by a bolt and the like, so as to cut a to-be-cut material as a cutter rotates.
Hereinafter, a related art insert tip will briefly be described with reference to FIG. 1 to FIG. 7.
FIG. 1 is a perspective view illustrating a cutter in which a related art insert tip is used. As shown, the related art cutter includes a cutter body 10 constituting a body, and an insert tip 20 fixed to the cutter body 10. The insert tip 20 fixed to the cutter body 10 cuts a to-be-cut material as the cutter rotates.
FIG. 2 is a perspective view illustrating an example of the related art insert tip, FIG. 3 is a plane view of FIG. 2, and FIG. 4 is a sectional view taken along line III-III of FIG. 3, illustrating the state that the insert tip is fixed to the cutter body.
First, the insert tip shown in FIG. 2 is a double-edged insert tip 20a and has a substantially hexahedral shape. The double-edged insert tip 20a cuts the to-be-cut material using a cutting edge provided at each corner portion of upper and lower surfaces. A bolt hole 21 is formed at a center area of the double-edged insert tip 20a to receive a bolt 30 therein, which fixes the double-edged insert tip 20a to the cutter body 10.
The bolt hole 21 is gradually tapered toward the center portion to insert a head portion of the bolt 30 therein.
In this case, the double-edged insert tip 20a may use the cutting edge at the upper surface. Alternatively, the double-edged insert tip 20a may use the cutting edge at the lower surface if it is reversed. Therefore, the inside of the bolt hole 21 is symmetrically formed up and down around its center portion.
FIG. 5 is a perspective view illustrating another example of the insert tip constituting the related art cutter, FIG. 6 is a plane view of FIG. 5, and FIG. 7 is a sectional view taken along line IV-IV of FIG. 6, illustrating the state that the insert tip is fixed to the cutter body.
The insert tip shown in FIG. 5 is a single-edged insert tip 20b and cuts the to-be-cut material using a cutting edge respectively provided only at four corner portions of an upper surface. A bolt hole 21 is formed at a center area of the single-edged insert tip 20b to receive a bolt 30 therein, which fixes the single-edged insert tip 20b to the cutter body 10.
Furthermore, since the single-edged insert tip 20b uses only the draw-out line at the upper surface, it does not have to be reversed. Therefore, the inside of the bolt hole 21 is not required to be symmetrically formed up and down, unlike the double-edged insert tip 20a. 
In the related art insert tips 20 constructed as above, a wrench (not shown) is inserted into a wrench insertion hole 31 of the bolt 30, and the bolt 30 is rotated to fix the insert tips 20 to the cutter body 10. Then, the cutter is rotated to cut the to-be-cut material.